Our proposed research will be focused on two major areas. First, we will study the abilities of normal hearing listeners to detect, discriminate, and identify target components of non-speech auditory patterns. Second, we will investigate individual differences in auditory capabilities in a population of audiometrically normal listeners. In our studies of discrimination of auditory patterns, we typically vary a target tone level adaptively using a rule that seeks that stimulus level required for a fixed probability of a correct response. Such adaptive tracks (records of stimulus levels used in the course of a test) reflect in some detail 1) parameters of the adaptive rule, 2) learning during the early portion of the test, 3) the observer's capability to perform the task after the track is stable, and 4) attentional shifts over the course of the test. We have on record many such tracks obtained during experiments on listeners' abilities to discriminate tonal sequences. We shall attempt to derive from these tracks parameters which reflect the factors mentioned above. The individual differences study will obtain distributions of performance measures using a range of auditory tasks from a population of audiometrically normal listeners, determine the amount of variance of these distributions accounted for by purely auditory capability, and whether this auditory capability predicts abilities to discriminate speech under difficult listening conditions.